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/* IBM_PROLOG_BEGIN_TAG */
/* This is an automatically generated prolog. */
/* */
/* $Source: src/include/util/lockfree/stack.H $ */
/* */
/* IBM CONFIDENTIAL */
/* */
/* COPYRIGHT International Business Machines Corp. 2010,2013 */
/* */
/* p1 */
/* */
/* Object Code Only (OCO) source materials */
/* Licensed Internal Code Source Materials */
/* IBM HostBoot Licensed Internal Code */
/* */
/* The source code for this program is not published or otherwise */
/* divested of its trade secrets, irrespective of what has been */
/* deposited with the U.S. Copyright Office. */
/* */
/* Origin: 30 */
/* */
/* IBM_PROLOG_END_TAG */
#ifndef __UTIL_LOCKFREE_STACK_H
#define __UTIL_LOCKFREE_STACK_H
#include <stddef.h>
#include <assert.h>
namespace Util
{
namespace Lockfree
{
template <typename _T>
class Stack
{
public:
Stack() : head(NULL) {};
_T* pop();
void push(_T*);
/**
* Get a pointer to the first element in the stack
* @return the pointer to the first element
* @Note: SMP safety of this pointer is not guaranteed.
*/
_T* first();
private:
_T* head;
};
template <typename _T>
_T* Stack<_T>::first()
{
_T * _head = head;
return (_T*) (((uint64_t)_head) & 0x00000000FFFFFFFF);
}
template <typename _T>
_T* Stack<_T>::pop()
{
_T * _head = head;
_T * h = (_T*) (((uint64_t)_head) & 0x00000000FFFFFFFF);
if (NULL == h) return h;
uint64_t token = ((uint64_t)_head) >> 32;
token++;
uint64_t h_next_v = (uint64_t)(h->next);
_T * h_next = (_T*) ((h_next_v & 0x00000000FFFFFFFF) |
(token << 32));
if (!__sync_bool_compare_and_swap(&head,
_head,
h_next))
return pop();
crit_assert((h_next_v >> 32) == 0x5354414B);
return h;
}
template <typename _T>
void Stack<_T>::push(_T* p)
{
_T* _head = head;
p->next = (_T*) ((((uint64_t)_head) & 0x00000000FFFFFFFF) |
0x5354414B00000000);
uint64_t token = ((uint64_t)_head) >> 32;
token++;
_T* _p = (_T*) (((uint64_t)p) | (token << 32));
if (!__sync_bool_compare_and_swap(&head,
_head,
_p))
push(p);
}
}
}
#endif
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